Miyajima N, Horiuchi R, Shibuya Y, Fukushige S, Matsubara K, Toyoshima K, Yamamoto T
Department of Oncology, University of Tokyo, Japan.
Cell. 1989 Apr 7;57(1):31-9. doi: 10.1016/0092-8674(89)90169-4.
Two erbA homologs, termed ear-1 and ear-7, are present in the human genome on chromosome 17. The two genes reside in the same genetic locus with overlapping exons and are transcribed from opposite DNA strands. In addition, the ear-7 mRNA is alternatively spliced to generate two protein isoforms, namely the ear71 and ear72 proteins. Nucleotide sequence analysis predicts that the ear71 protein is a human counterpart of the chicken c-erbA protein, a molecule closely related or identical to thyroid hormone receptor. Indeed, Scatchard analysis of proteins synthesized in vitro indicated very high affinity binding of T3 to the ear71 protein but not to the ear72 protein. Interestingly, the ear-1 gene product showed low, but appreciable, binding to T3, although its authentic ligand remains to be clarified.
人类基因组17号染色体上存在两个erbA同源基因，分别称为ear-1和ear-7。这两个基因位于同一基因座，外显子重叠，且从相反的DNA链转录。此外，ear-7 mRNA可选择性剪接，产生两种蛋白质异构体，即ear71和ear72蛋白。核苷酸序列分析预测，ear71蛋白是鸡c-erbA蛋白的人类对应物，该分子与甲状腺激素受体密切相关或相同。事实上，对体外合成蛋白质的Scatchard分析表明，T3与ear71蛋白具有非常高的亲和力结合，但与ear72蛋白没有结合。有趣的是，尽管ear-1基因产物的真正配体仍有待阐明，但它与T3的结合亲和力较低，但仍相当可观。
